i) Field of the Invention
The present invention relates to a novel tricyclic compound having an excellent antimicrobial activity and oral absorbability and salts thereof, a method for producing the same and an antimicrobial agent containing the same.
ii) Description of the Background Art
Conventionally, in compounds including a pyridone-carboxylic acid as a basic skeleton, many compounds having an excellent antimicrobial activity and a wide antimicrobial spectrum are known as a useful synthetic antimicrobial drug or agent. For instance, norfloxacin (see Japanese Patent Laid-open (Kokai) No. 53-141286), enoxacin (see Japanese Patent Laid-open (Kokai) No. 55-31042), ofloxacin (see Japanese Patent Laid-open (Kokai) No. 57-46986), ciprofloxacin (see Japanese Patent Laid-open (Kokai) No. 58-76667) and the like are widely used as an infective disease remedy in clinical medicine.
However, these compounds are still insufficient in antimicrobial activity, enteron absorbability, metabolic stability, side-effects and the like, and hence a novel compound satisfying these requirements has been demanded.